Chemical shift artifact in clinical magnetic resonance images at 0.35 T

A thin, low-intensity line, which partially surrounds many structures on magnetic resonance imaging (MRI), is an artifact due to the phenomenon of chemical shift and should not be mistaken for a normal or abnormal morphologic structure. This artifact can be recognized by its characteristic appearance perpendicular to the direction of the frequency-encoding gradient at the interface of tissues with different chemical shift properties. Confinement within or extension beyond this thin, low-intensity line cannot be used as a criterion for staging neoplasms. Once recognized, the chemical shift artifact should not impede the use of MRI for clinical imaging at 0.35 T.     

Atlanto-axial instability and spinal cord compression in children--diagnosis by computerized tomography

Five children who were at risk for atlanto-axial instability underwent computerized tomography scanning of the cervical spine in flexion and extension to document the degree of bone instability and the presence or absence of spinal cord compression. Two patients had Morquio's syndrome, two had os odontoideum , and one had Klippel-Feil syndrome, and in all five the lateral radiographs of the cervical spine in flexion and extension were equivocal with regard to instability or were difficult to interpret because of the bone anomalies. The computerized tomography scan then provided a diagnosis by a non-invasion technique and quantitated the amount of compromise of the spinal cord by delineating flattening of the cord. The scan therefore helped the surgeon to decide if the spinal cord was at significant risk and if atlanto-axial fusion was advisable.     

苯甲吗啉类药物的代谢及代谢产物的研究

本文报道苯甲吗啉类药物的气相色谱与气质联用检测方法。用HP-5890A气相色谱仪、氮专属性检测器,对服药后不同时间排尿中原型药及主要代谢产物,以内标法定量测定,绘制尿累积排泄曲线.醚提取物用三氟醋酐衍生化、气相色谱、气质联用分析比较衍生化前后保留时间及质谱数据,鉴定主要代谢产物苯甲吗啉,微量代谢产物去甲麻黄素、去甲伪麻黄素、麻黄素和伪麻黄素,方法灵敏、结果可靠,适用于此类药物的临床监测与运动员尿样检测。     

Cerebrospinal fluid analyses in migraine patients and controls

To investigate the role of central neurotransmitters in the pathogenesis of migraine, we measured cerebrospinal fluid (CSF) levels of certain amino acids (glycine, taurine, glutamine) and metabolites of biogenic amines (5-hydroxyindoleacetic acid and homovanillic acid) in 38 migraine patients and compared them with the levels from 10 headache-free controls. The levels of taurine, glycine and glutamine were significantly higher in the migraine patients (p < 0.0001 for taurine and glycine; p < 0.0009 for glutamine); there were no significant differences among the three migraine subgroups (infrequent migraine, frequent migraine and transformed migraine). In seven patients subsequently treated with divalproex sodium, CSF taurine levels decreased significantly from pretreatment baseline values. These data support the concept that migraine is at least in part a disorder of central neurotransmission.     

Plaque accumulation on different dental filling materials

abstract — The purpose of the present study was to investigate whether some dental filling materials collect more plaque than others under standardized conditions in vitro and in vivo . Round disks of the filling materials of silicate, composite and amalgam were prepared and placed on an agar/sucrose medium or hung in liquid medium containing 5% sucrose. The mediae were inoculated with Streptococcus mutans OMZ 176 and OMZ 52–3. After 6 d the disks were rinsed in distilled water and the plaque that had accumulated on the surfaces was scraped off and measured by the orcinol method. The materials were also fitted to acrylic plates and introduced into the mouth. Six patients wore two plates each for comparison of the materials and were told to rinse their mouth every hour with 15% sucrose solution. After 8 h the plaque was scraped off and measured. Silicate disks on agar medium invariably produced inhibition zones of about 4 mm. Composites and amalgam showed no such zones. In liquid medium an insignificant amount of plaque was absorbed to the silicate disks, whereas abundant amounts were found on composite materials and some on amalgam disks. The same trend could be demonstrated in the clinical experiments.     

Magnetic resonance imaging of the lumbar spine with CT correlation

The results of magnetic resonance (MR) imaging and computed tomography (CT) in 18 patients with known degenerative disk disease of the lumbar spine were compared. In 60 intervertebral disk levels studied, there were 17 disks with degeneration and disk bulge, and 15 herniated disks. Final diagnoses were based on several factors, with surgical confirmation in five patients. There was good correlation between the two methods at 51 of the 60 levels studied. However, there were major discrepancies in interpretation at nine intervertebral disk levels. These included three false-positive MR imaging interpretations of a herniated disk and one false-negative herniated disk on MR imaging. MR imaging detected one case of disk herniation that was missed prospectively on CT. There were also four presumed degenerated disks seen on MR scans that appeared normal on CT. The conus medullaris was imaged in 16 of 18 patients. The sagittal view proved best for demonstrating both disk abnormality and the conus medullaris. The transaxial view was sometimes helpful in localizing a disk herniation, but partial-volume averaging in the 7-mm slice thickness limited its usefulness. There were five disk herniations that could not be accurately localized on the MR scan. MR imaging proved more sensitive than CT in detecting early disk disease, which appeared as decreased signal intensity within the disk. In three postoperative cases, MR imaging was better able to distinguish between recurrent disk herniation and postoperative scar formation. CT, on the other hand, was more specific in distinguishing herniated disk from disk bulge and proved far superior to MR imaging in localizing disk herniation.(ABSTRACT TRUNCATED AT 250 WORDS)     

Recovery from primary pontine hemorrhage

A patient with primary pontine hemorrhage showed typical ocular bobbing with only mild alteration of mental status. Serial CT scans showed resolution of the hemorrhage and correlated with clinical improvement.